Scientists Spot More Genes Related to Alzheimer's

MONDAY June 14, 2010 -- Researchers report that they have spotted two new regions of the human genome that may be related to the development of Alzheimer's disease.

The findings, published in the June issue of the Archives of Neurology, won't change the lives of patients or people at risk for the devastating dementia just yet, however.

"These are now new biological pathways to start thinking about in terms of finding drug targets and figuring out what really causes Alzheimer's disease," explained study senior author Dr. Jonathan Rosand, a faculty member with the Center for Human Genetic Research at Massachusetts General Hospital and an associate professor of neurology at Harvard Medical School in Boston.

Maria Carrillo, senior director of medical and scientific relations at the Alzheimer's Association, believes findings such as this one will eventually usher in an era of "personalized medicine" for Alzheimer's, much like what is being seen now with cancer.

"Perhaps some day in the future, all this information can be put into a bucket and given a bar code, which [represents] your risk for Alzheimer's," she said, while cautioning, "we're not there yet."

Although scientists have known that Alzheimer's has a strong genetic component, only one gene -- APOE -- has been implicated and in early-onset disease.

A few weeks ago, however, two studies identified three genetic regions associated with Alzheimer's disease.

Now Rosand and his colleagues have looked at genetic and neuroimaging data on the brain structures of 168 people with "probable" Alzheimer's disease (Alzheimer's can't be definitively diagnosed until a brain autopsy has been conducted), 357 people with mild cognitive impairment and 215 normal individuals.

"Basically, they were looking to see if some of the imaging results were changed in people with Alzheimer's disease who also had these types of genetic variations," Cirillo said.

The study confirmed that APOE is still the dominant gene when it comes to Alzheimer's, while the three more recently identified regions seemed to have an additive effect.

In addition, the authors "found two new areas that were associated with some of the MRI changes of Alzheimer's disease that hadn't been implicated in previous studies of Alzheimer's," Rosand said.

The next step is to figure out what these genes do. Right now, scientists only know that "they encode proteins that are involved with the growth of neurons, the integrity of neurons and the function of neuronal transmission, but beyond that we don't know," Rosand said.

"It's very important that these types of genes are localized and fleshed out, and that the basic biology of why they are making changes is discovered," Cirillo said.

In addition to predicting risk, the genetic variants could be potential targets for both prevention and treatment of Alzheimer's, although that's way down the line.

More information

Visit the Alzheimer's Association for more on this degenerative disease.

Posted: June 2010


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